Fluid actuated impact tool



May 12, 1964 R. BAsslNGER ETAL 3,132,704

FLUID ACTUATED IMPACT TOOL.

Filed Dec. 5, 1960 4 Sheets-Sheet 1 NVENTORJ BY/ M m0/L7 May 12, 1964 R. BAsslNGl-:R ETAL 3,132,704

FLUID ACTUATED IMPACT Toor. Filed Deo. 5, 1960 4 Sheets-Sheet 2 /a/77eJ @aro/ner INVENTORJ /1 7 7' ORA/E VJ May 12, 1964 R. BAsslNGER ETAL 3,132,704

FLUID ACTUATED IMPACT TOOL Filed Deo. 5, 1960 4 Sheets-Sheet 3 PoJJ Bava/yer dames Gora/0er INVENTORJ May 12, 1954 R. BAsslNGER ETAL 3,132,704

FLUID ACTUATEID IMPACT TOOL Filed'Dec. 5, 1960 4 Sheets-Sheet 4 United States Patent O Tex.

Filed Dec. 5, 1951i, Ser. No. 73,611 Claims. (Cl. 173-71) This invention relates to improvements in fluid actuated impact tools of the type especially adapted to be operated by a pneumatic medium such as compressed air or steam. It is particularly directed to improvements in uid actuated impact tools such as those described in U.S. Patent No. 2,859,733 and in U.S. Patent No. 2,943,663. In one aspect it relates to a tool of this class having an improved valving arrangement for reciprocating t .e hammer, and in another aspect it relates to valving arrangements particularly effective in increasing the frequency of reciprocation of a hammer in such tools.

In impact tools, the type of which this invention relates, power uid is applied to endwise surfaces of a reciprocable hammer to drive the hammer in both power and return strokes. The application of actuating uid to the hammer is controlled by a valve means arranged so that pressure from the power fluid on a surface of the hammer is effective to drive the hammer in a power stroke but is ineffective to prevent the hammer moving in its return stroke.

For example, it has been suggested that a hammer in a tool of this type be provided with a passageway for power uid through the hammer and that fiow of power uid through the passageway be controlled by a fingerlike valve element which telescopes into and out of the passageway, thus closing and opening the passageway to ow of fluid. Such fingerlike valve closure members may be stationary and fixed to a stationary part of the impact tool, or they may be of diving or reciprocating type. In either case, alternate closing and opening of a passageway through the hammer increases and decreases the pressure of the power fluid applied to the hammer thus moving the hammer in a power stroke at increased pressure and permitting it to move in a return stroke against slightly decreased pressure.

In the diving finger type tool, the hammer moves toward the finger until the finger begins to enter the passageway through the hammer. The finger then plunges, or dives, into the hammer passageway for a predetermined distance. As a result the portion of the stroke through which full pressure of power fluid is applied to drive the hammer through its power stroke is lengthened by maintaining closure of the passageway-through the hammer.

The total length of the power stroke will be the sum of the overtravel of the hammer plus the distance the finger moved, the term overtravel being applied to the distance the hammer moves after the passageway is blocked by insertion of the finger and before power fluid reverses the direction of movement. In the fixed finger type tool, there is no diving movement of the finger into the passageway through the hammer, and the length of the power stroke depends upon overtravel unassisted by movement of the finger.

The present invention is directed to improvements in uid actuated impact tools of either the fixed finger or diving finger type. It will be obvious that the total effect of a tool of this type is a function of the number of strokes delivered per minute and the force applied in each stroke.

It is an object of this invention to provide a valving lddd Patented May l2, 1964 ICC rangement which shortens the time required for actuating fluid to begin moving the hammer in its power stroke.

Another object is to provide a means for utilizing movement of the hammer in its return stroke for increasing pressure applied upon a face of the hammer to start the hammer in a power stroke.

Another object is to provide a unique valving arrangement which traps and further compresses power fluid in the inlet portion of the tool adjacent to the power face of the hammer during return stroke of the hammer and provides maximum pressure at the instant required to overcome inertia of the hammer.

Another object is to provide such valve means which is simple and cheap in construction, strong, rugged and dependable in operation and is not subject to excessive metallic fatigue.

In the present invention a check valve is provided in a branched passageway for actuating fluid between the inlet to the tool and the power face of the hammer which closes instantly during the return stroke upon the finger entering the passageway through the hammer. As the return stroke continues, power fluid trapped in the body of the tool between the advancing face of the hammer and the check valve is further compressed by the momentum of the hammer which is moving at high velocity. When the lower finger valve opens and releases driving pressure for the return stroke, the highly compressed uid ahead of the moving hammer quickly stops the motion of the hammer. At this instant when the power uid is under highest compression and the hammer is at rest, maximum force is exerted on this hammer. This condition occurs at the instant of greatest need for power required to overcome the inertia of the hammer and to start the hammer on its power stroke. As ther power stroke progresses, the power uid in contact with the hammer face expands until its pressure approaches that of the uid at the inlet to the tool. The check valve opens and admits power fluid to complete the power stroke and that portion of the return stroke prior to opening of the lower finger' valve. This new valving arrangement has increased the'stroke frequency of a tool of this type by about 40 percent.

The check valve preferably is actuated by a weak spring disposed to close the valve at any time when pressure upon the power surface of the hammer exceeds a value lower than inlet pressure by a small amount determined by the strength of the spring. Preferably this valve is annular and is disposed in the tool around the linger to close all branches of a branched power uid inlet simultaneously.

While it is quite possible to utilize a plurality of check valves, one disposed to close each branch of the passageway for power fiuid around the finger, such arrangement is not preferred because the valves must be made quite small and their small size makes them sufficiently fragile that they cannot withstand long periods of heavy use at speeds of several thousand strokes aminute without developing metallic fatigue or becoming badly worn. Also a single valve might be disposed in the main inlet passageway for power uid, but the size of a check valve in this location makes it a less preferred arrangement. A`

o) fcrred modification o' the check valve of the present invention.

FIG. is a cross section through the tool of FIG. 4 on the line 5 5 of FIG. 4; and

FG. 6 is a cross section through the tool of FG. 4 on the line 6-6.

HGS. 7, 8 and 9 are schematic representations of a tool of reciprocating or diving linger type, improved according to the present invention, in succeeding parts ci the power and return strokes.

FG. 10a is a detail of the inlet end of a diving linger tool constructed according to the present invention showing a preferred type of check valve arranged to cooperate with the diving finger valve of this tool.

FIG. 1Gb illustrates an end of the tool opposite to the end shown in FlG. 10a and is a continuation of FIG. 10a downward.'

Generally, the apparatus illustrated in FIGS. 1, 2 and 3 includes a hammer 16 mounted for reciprocation within and relative to a hollow body 11. The hollow interior of body 11 serves as a conduit means for applying actuating iluid and comprises an inlet constructed as a single large bore 12 adapted to be connected at 13 to a. conduit for power rluid. A plurality oi branch openings 14 communicate with the bore 12 and a space 15 between the branch openings 14 and an upper face 16 of hammer lil.

Pneumatic fluid under pressure entering the inlet bore 12 liows through openings 1d in the branched portion of the power iiuid conduit into space 1S and exerts pressure on face 1d of the hammer to drive the hammer downward until it strikes a face 17 of an anvil 13.

A cheek valve 1?, which is preferably an annular member, is disposed transversely to the direction oi iuid dow to open and close all of openings 1li in the branched portion of the huid conduit simultaneously. The valve closure member 19 is'suspended from and urged upward by a plurality of weak springs 2.1 singly disposed in each of openings 14 and suspended therein from pins 22. Since springs 21 are quite weak, the valve closure member 19 presents little resistance to ow of actuating iluid from inlet bore 12 to the duid conduit section 15 between the check valve and the hammer face 16.

1n the ixed linger i'orm illustrated in FIGS. 1 to 6, the tool includes upper and lower valve closure members, or lingers, 23 and 2d arranged so that when the upper valve closure member, or linger, '23 enters and closes a passageway 25 through the hammenthe hammer may be moved through a power stroke by power luid entering from bore 12 ultimately to deliver a blow to the anvil 18. Then, upon opening of the upper valve means by withdrawal of finger 23 from opening 25, pressure oi power fluid acts to move the hammer in a return stroke to complete the cycle. In order to conserve power fluid, the arrangement is such, as will be explained in detail below, at leasty one of the valve closure members,` or lingers, restricts flow through the tool at substantially all times soV that freelow of duid without exerting a desired actuating force on the hammer is prevented.

At an instant before the end of the power stroke, as illustrated in FlG. 1, power duid is llowing from bore i?. through openings 1d space 15, conduit 25, and an annular space Ze around the lower end of the' hammer and is applying pressure upon a lower face 27 of the hammer tending to force the hammer upward. Since the lower end ofthe hammer has a larger effective piston surface than the upper face 16, the hammer moves upward against pressure of actuating duid in space 15. Before the lower finger 2d is withdrawn from an opening 28 through the anvil and the upper linger 23 closes passageway 25 through the hammer, a considerable volume oi actuatingfluid under pressure is accumulated in passageway 25, annular space 2o and a space betweenthe faces 27 of the hammer andv 17 of the anvil. Momentum of the hammer and pressure from this volume of fluid continues to move the hammer upward until pressure of fluid in space 25 approaches the ment relative to each other and yet relative rotation bcpressure at which actuating Huid is delivered to the tool. At this time, valve closure member 19 snaps shut as is shown in FG. 2, thus trapping fluid in the space 1S between the hammer and valve closure member 19. Momentum of the hammer, which is traveling at high speed, carries the hammer upward, further compressing the air or other actuating fluid in space 15. Asfthe hammer reaches its upper limit of travel, the pressure of actuating iiuid in this space is at its maximum at the exact instant at which maximum power is required to overcome inertia o the hammer and start the power stroke.

Turning now to a detailed description of the tool as shown in FIGS. 4 to 6, 1the hollow interior of the tool functioning as a fluid supply conduit comprises an inlet section 2:9 having a large central bore 12 and is provided at its upper end with a suitable connection to a conduit for actuating fluid (not shown). This connection may be a standard tool box or pin for connection with a drill string so that power iiuid can be connected to the tool through the drill string; and as the tool sinks lower and lower into a bore hole, the tool can be rotated and its position otherwise regulated by suitable manipulation of the drillv string. For ease in assembly the hollow body preferably comprises an upper section 29 containing the bore `12, a valve enclosure section 31 and a lower section 32. Sections 29, -31 and 32 preferably are iXedly connected together by suitable threads 33 and 34.

The hammer 1d preferably is'of one piece construction and is disposed to reciprocate wif lin sections 31 and 32. It is provided with an upper piston face 16 of smaller diameter than the cross section of the lower part 34 of the hammer.

The upper valve closure member, or linger, 23 is iixed to the upper inlet section 29 and is preferably integral therewith. The upper part of the passageway through hammer .1d ts snugly upon nger 23 and preferably is surrounded by labyrinth grooves 35 to decrease leakage of actuating iluid around the -finger.

The annular valve member 19 is disposed around linger 23 to close all openings 14 forming the branched section of the actuating fluid supply conduit. Closure member 19 is equipped with hns 36 extending into openings 14 and maintaining the closure member 19 centered upon the lower end of the openings. The closure member is biased upward by weak springs 21 disposed in each of openings 14 and thus maintaining balance of member 19. Pins 37 extending from the outside of the tool through an annular groove 38 communicating wit-h the inlet section 12 and with openings 14 are arranged to support springs Z1.

The anvil 18 of FlGS. l to 3 is disposed in a hollow interiorcf housing 11 for limited reciprocal motion and serves as a holder for a suitable tool, illustrated as a drill bit 39. While many arrangements 'of anvil and tool elements carried thereby may be used in the device of this invention, one preferred arrangement illustrated Will be described for the purposes of completeness. In the device illustrated in the drawings, means are provided for slidably connecting anvil 18 to the housing so that the housing and anvil can have limited longitudinal movetween them is substantially prevented. The purpose of a connection of this type is twofold in that it provides a n torque Vtransmitting connection for rotating the anvil and a working tool such as bit 39 attached thereto, by rotation of a drill string attached to ,the upper end of 'housing 11. Rotation of the drill string enables the bit to be rotational-1y indexed to ltake a new bite of the working faceof the bore hole without applying such torque to the hammer in a manner to interfere with its reciprocation. A sliding connection also permits the bit to drop away or' drill away from the housing when the latter is being moved too slowly to keep up with the bit so as to reduce the impact energy of the hammer and thereby avoid damaging the connection of the fluid supply conduit means.

It also provides a means for supporting the anvil and bit as the tool is being lowered into a bore hole Iuntil the bit encounters a working face of the hole and it permits changing the beating frequency of the hammer withou-t withdrawing the tool from the bore hole as will be explained in more detail later.

In a preferred form the connective means comprises a plurality of longitudinally extending splineways in the anvil and in a lower part of the housing. These splineways are arranged -in matched pairs. A splineway 41 of each pair being located in the anvil and a second splineway 42 in a lower part of the hou-sing. The opposing splineways 41 and 42 are radially aligned and suitable bridging elements illustrated as roller bearings 43 are disposed in the splineway to transmit torque between the lower part of the housing and the anvil while permitting relative longitudinal movement between the housing and anvil.

In order to hold the anvil in proper axial alignment with the housing without imposing any substantial aligning stresses on the bridging elements or splineways, the anvil preferably is provided with an upper piston part 44 and another piston portion 45, each having a close sliding bit in the lower part of the housing. Since the two piston parts 44 and 45 are spaced apart longitudinally, they provide axially aligned bearing points maintaining the anvil in axial alignment during reciprocation of the anvil. The anvil is Ithus freely slidable through a distance limited -by the travel of splineway 41.

The lower end of the tool just described is substantially identical with :that shown in FIGS. 7 to 9, inclusive, and it is to be understood that in all these ligures tools of other kinds may be substituted for the drill bit 39 if desired.

FIG. 10b is an enlarged detail of the tool connection shown schematically in FIGS. l to 3 and 7 to 9 and particularly illustrates a method for assembling the tool. The lower portion of the body 32 is preferably threaded at 46 with tapered threads designed to take a split nut 47. 'Ihe nut 47 preferably is vertically divided into two semi-annular halves, and the division occurs upon splineway 42 in the nut. In assembling the tool, the bridging members 43 are placed -in the splineways 42 and 41 while the vertical halves of the nut are separated. The halves of the split nut are placed in contact surrounding the bridging members and -are held together by a pin 4S and are then screwed rigidly into position by means of threads 46. The interior ofra lower part of nut 47 forms a cylinder in which a piston portion 45 of the hammer 25 is longitudinally slidable. A passageway for actuating liuid through the hammer 28 communicates with branched passageways 49 in the bit shown sothat the exhaust of actuating uid occurs at the face of the work and assists the drill bit by removal of chips cut from the bottom of the hole.

The upper face 17 of the anvil preferably is shaped to' avoid full contact of all its area with the opposing face of the hammer so that at the moment of impact there is suliicient space for compressed pneumatic liuid to flow between the hammer and anvil faces to exert pressure for the return stroke. If desired, grooves Slalso may be cut in the hammer or anvil face to assist in the distribution of such pneumatic luid.

The upper end of the hammer preferably is equipped with labyrinth grooves 52 for reducing leakage around the hammer, but a small amount of leakage can be permitted and is desirable. A slight leak of pneumatic `fluid around the hammer past labyrinth grooves 52 into an annular space 53 around the hammer results in an outward flow of liuid through passageway 54 into the atmosphere, or well cavity, around the body of the tool. Parssageway 54 is normally closed by an O-ring seal 55 which prevents the entrance of dust, grit and undesirable sub\ @t stances which might increase friction of the hammer with the interior of the body. A slight outliow of fluid through passageway 54 at all times prevents such entrance of foreign material.

The valving arrangement of the tool shown in FIGS. 7 to lila differs from that described above in that a reciprocating .or diving finger valve closure member is used. The supply conduit for actuating liuid comprises a central bore 12 in an inlet portion of the housing which communicates with a space 56 between an upper face of the hammer and the valve arrangement S7 to apply actuating pressure to the upper surface 16 of hammer 18.

As a part of the valve or liow control means, the reciprocable hammer 10 is provided with a passageway 2S which acts as a valve element cooperating with a reciprocable linger member 52 to open and close passageway 25 to llow of actuating fluid. Finger member 52 preferably has a sufficiently close lit in the, upper part of passageway 25 as to substantially block liow therethrough and labyrinth grooves 58 may be provided in the upper part of passageway 2S to aid in stoppage of flow.

In accordance with this invention, the arrangement is such that the finger member 52 reciprocates between retracted and extended positions, the retracted position being more remote from the hammer than the extended position. The arrangement is such that the linger will be in retracted position until the hammer, after it has struck a blow upon the anvil, moves in its return stroke far enough that the tip of linger 52 begins to enter the upperpart of bore 25. Thereafter, on pressure in passageway 25 dropping as a result of restriction of actuating uid flowing thereinto, linger will move or dive into the hammer bore 25 until it reaches its extended position. It remains in extended position until movement of the hammer in its return stroke is reversed, and the harnmer is moved through at least a portion of its power stroke sufcient to disengage the tip of linger member 52 from the upper end of passageway 2S. During the final movement of the hammer in its power stroke, passageway 25, moves out of telescopic relation with the nger whereupon the linger moves into retracted position.

To provide this action for the linger element, it is made with larger and smaller piston portions 59 and 61, respectively. The means for reciprocatingthe finger includes a smaller cylinder 62 containing the smaller piston portion 61 and a largerA cylinder 63 in which the larger piston portion of the linger 59 reciprocates. A small passageway 64 is disposed to admit actuating liuid from inlet bore 12 at all times.

The conduit for actuating fluid has a branched portion composed of a plurality of openings 14 communicating with the inlet bore 12 and space 56. An annular valve closure member 19 having upright guide fins 36 disposed in each of passageways 14 is disposed to open and close all of said passageways simultaneously. Valve closure member 19 is suspended on a plurality of weak springs 21 singly disposed in each of passageways 14 and carried by pins 37. The valve closure member 19 is thus urged upward at all times by the tension of springs 21 and functions as a check valve to prevent back liow of pneumatic liuid from the space 56 into the inlet bore 12.

The cooperation of this check valve 19 with the diving linger 52 is best understood by reference to FIGS. 7, 8 and 9. In FIG. 7 the hammer 10 is approaching the end of its power stroke at the instant before impact with the upper face of anvil 18. Actuating lluid is flowing from inlet bore 12 through openings 14 around springs 21 and is maintaining the check valve 19 in unseated position allowing free flow of liuid. The actuating iiuid pressure is applied to the upper surface of the hammer, driving it downward and liuid is owing through-passageway 25 and branched passageways 65 into the annular space 26 around thelower end of the hammer and communicating with space between the hammer and the anvil.

In this position the full pressure of actuating fluid is 7 applied through the small openings 6d on the smaller upper piston end 61 of the finger; but the fullrforce of the actuating fluid also is applied upon the larger piston portion 59 of the iinger, and the nger is thus forced upward to the full limit of its travel.

After impact, actuating pressure exerted on the larger lower end of hammer itl starts the hammer in its return stroke. After the hammer has traveled through a portion of its return stroke, the parts will have the relative position shown in FIG. 8. In this position the lower finger member 2d has been withdrawn from passageway 28 through the anvil by upward movement of the hammer thus releasing pressure in passageways 25 and 28. In the position shown, the upper or diving finger has engaged the upper part of passageway 25, thus lowering pressure on the underside of piston 59 by at least partially exhausting huid from cylinder 63 through a vent 5t) (shown only in FIG. 10a) and the hollow interior of iinger 52.

The relative proportions of pistons 59 and 64 are so chosen that the full pressure of actuating duid from inlet bore 12 entering through opening ed is sufcient to overcome pressure on the lower side of piston 59 and move the finger 52 downward for the full length of its travel, thus effectively closing off passageway 25.

The upward momentum of the hammer, which is traveling at high speed, compresses the pneumatic fluid in space 56. In the position shown in FIG. 8 the pressure in space 56 has substantially equaled that in the inlet bore 12 with the result that the springs 21 have drawn the annular valve closuremember 19 into position to close oif all openings FA. It will be obvious that additional upward travel of hammer lll will further compress gas in this space until the hammer reaches its upper limit of travel. At this point where maximum power -is required to overcome inertia of the hammer and start the hammer upon its power stroke, pneumatic fluid in space 55, under pressure far exceeding that in inlet bore 12, is available to perform this function and the frequency of reciprocation 0f the hammer is greatly increased.

In the position of parts shown in FIG. 9, the power stroke has continuedv through a distance such that the pneumatic fluid compressed in space Se has dropped in pressure sufficiently to permit check valve 19 vto be opened by inlet pressure. Actuating iiuid is iiowing from bore l2 through openings 1d into space 56 where it exerts its full force upon the upper face of hammer 10. In the position shown, the lower finger 24 is beginning to engage bore 23 through the anvil and the finger 52 is about to be withdrawn from bore 25 in the hammer by movement of the hammer. It will readily be seen that the application of the full pressure from bore 12 to the upper face of the hammer in the reciprocating finger tool will be continued for an increased time depending upon the distance through which finger 52 reciprocates. At the instant finger 52 emerges from bore 25 of the hammer, the full force of the actuating fluid is applied through Vent passageway 5t) on the lower face of piston 59 and is suticient to overcome the force on piston tid and to drive the finger into its retracted position,

Thus, it will be seen that the improved valving arrangement of this invention results in a tool in which the frequency of reciprocation is greatly increased whether the finger type valve performing the main valving function and applying pressure to opposite ends of the hammer be of the lixed linger or reciprocating finger type. T here is always a point at the upper limit of the stroke of the hammer where pressure on a unitarea of the hammers upper face is much greater than the inlet pressure in bore 12. This occurs at the exact instant when the greatest power is needed, and the lag between return stroke and power stroke is shortened.

From the foregoing it will be seen that this invention is one well adapted to attain all of theends and objects hereinabove set forth, together with other advantages Y s which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcornbinations are of utility and may be employed without reference to other features and subcornbinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention Without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustra-tive and not in a limiting sense.

The invention having been described, what is claimed is:

1. An impact tool powered by a compressible iiuid which comprises in combination a housing; an inlet for actuating fluid into the housing; an anvil mounted in the housing for limited reciprocating movement; a hammer mounted between the inlet and anvil and reciprocable in the housing to beat upon the anvil, said hammer having endwise surfaces of dierent areas against which pressure from fluid in the housing can act to urge the hammer in power and return strokes; a first fluid .passageway through the hammer extending between said surfaces; a second fluid passageway through the anvil extending from a surface of the anvil opposed to the hammer to the exterior of the tool; a rst valve closure member, carried by the housing, disposed to open and close said first passageway after finite movement of the hammer in power and return strokes, respectively; a second valve closure member, carried by the hammer, disposed to close and open said second passageway after finite movement of the hammer in power and return strokes, respectively, said 'valve closure elements being cooperable to apply pressure from fluid in the housingy alternately to said endwise surfaces of the hammer vand too reduce pressure on the endwise surface opposite to the one upon which pressure is applied; and a check valve biased against inlet pressure disposed in an inlet portion of the housing to prevent reverse flow of actuating iiuid into the inlet, said check valve, housing, hammer and first valve closure member being cooperable to provide a closed small volume charnber in the housing when said first passageway is closed by said first valve closure member. n

2. An impact tool powered Vby a compressible Viiuid which comprises in combination a housing; an inlet for actuating fluid into the housing including a section havinga plurality of openings therethrough; an anvil mounted in the housing for limited reciprocating movement; a hammer mounted between the inlet and anvil and reciprocable in the housing to beat upon the anvil, said hammer having endwise surfaces of different areas against` which pressure from uid in the housing can act to urge the hammer in power and return strokes; a first fluid passageway through the hammer extending between said surfaces; a second fluid passageway through the anvil extending from a surface of the anvil opposed to the hammer to the exterior of the tool; a first valve closure member, carried by the housing, disposed to open and close said lirst passageway after finite movement of the hammer in power and return strokes, respectively; a second valve closure member, carried by the hammer, disposed to close and open said second passageway after finite movement of the hammer in power and return strokes, respectively, said valve closure elements being cooperable to apply pressure from fluid in the housing alternately to said endwise surfaces of the hammer and to reduce pressure on the endwise surface opposite to the one upon which pressure is applied; and a check valve in said inlet section biased againstV inlet pressure disposed to close all openings in said section simultaneously to prevent reverse'flow of actuating fluid into the inlet, said check valve, housing, hammer and rst valve closure member being cooperable to provide a closed small volurne chamber in the housing when said first passageway is closed by said first valve closure member.

3. An impact tool powered by a compressible fluid which comprises in combination a housing; an inlet for actuating fluid into the housing including a section having a plurality of openings therethrough symmetrically arranged on the circumference of a circle; an anvil mounted in the housing for limited reciprocating movement; a hammer mounted between the inlet and anvil and reciprocable in the housing to beat upon the anvil, said hammer having endwise surfaces of different areas against which pressure from fluid in the housing can act to urge the hammer in power and return strokes; a first fluid passageway through the hammer extending between said surfaces; a second passageway through the anvil extending from a surface of the anvil opposed to the hammer to the exterior of the tool; a first valve closure member carried by the housing disposed to open and close said liirst passageway after finite movement of the hammer in power and return strokes, respectively; a second Valve closure member carried by the hammer disposed to close and open said second passageway after finite movement of the hammer in power and return strokes, respectively, said valve closure elements being cooperable to apply pressure from uid in the housing alternately to said endwise surfaces of the hammer and to reduce pressure on the endwise surface opposite to the one upon which pressure is applied; and an annular check valve closure member biased against inlet pressure disposed to close all openings in said inlet section simultaneously to prevent reverse flow of actuating fluid into the inlet, said check valve, housing, hammer and iirst valve closure member being cooperable to provide a closed small volume chamber in the housing when said first passageway is closed by said rst valve closure member.

4. The impact tool of claim 3 wherein the check valve closure member has guide fins slidably disposed in each of said openings maintaining the valve closure member centered on each of the openings.

5. The impact tool of claim 4 wherein the valve closure member is biased against inlet pressure by a plurality of springs singly disposed in each of said openings and maintaining a balanced tension on said closure member.

6. An impact tool powered by a compressible iiuid which comprises in combination a housing; an inlet for actuating uid into the housing; an anvil mounted in the housing for limited reciprocating movement; a hammer mounted between the inlet and anvil and reciprocable in the housing to beat upon the anvil, said hammer having endwise surfaces of different areas against which pressure from fluid in the housing can act to urge the hammer in power and return strokes; a first fluid passageway through the hammer extending between said surfaces; a second iiuid passageway through the anvil extending from a surface of the anvil opposed to the hammer to the exterior of the tool; a first valve closure member carried by the housing in fixed position, disposed to open and close said first passageway after finite movement of the hammer in power and return strokes, respectively; a second valve closure member carried by the hammer in fixed relationship thereto, disposed 4to close and open said second passageway after finite movement of the hammer in power and return strokes, respectively, said valve closure elements being cooperable to apply pressure from the fluid in the housing alternately to said endwise surfaces of the hammer andto reduce pressure on the endwise surface opposite the one upon which pressure is applied; and a check valve in an inlet section of the housing biased against inlet pressure arranged to prevent reverse iiow of actuating fluid into the inlet, said check valve, housing, hammer and first valve closure member being cooperable to provide a closed small volume chamber in the housing when said first passageway is closed by said first valve closure member.

7. An impact tool powered by a compressible fluid which comprises in combination a housing; an inlet for actuating liuid into the housing, including a section hav-4 ing a plurality of openings therethrough; an anvil mounted in the housing for limited reciprocating movement; a hammer mounted between the inlet and anvil and reciprocable in the housing to beat upon the anvil, said hammer having endwise surfaces of different areas against which pressure from fluid in the housing can act to urge the hammer in power and return strokes; a first iiuid passagewaythrough the hammer extending between said surfaces; a second fluid passageway through the anvil extending from a surface ofthe anvil opposed to the hammer to the exterior of the tool; a first valve closure member carried by the housing in fixed position, disposed to open and close said first passageway after finite movement of the hammer in power and return strokes, respectively; a seco-nd valve closure member carried by the hammer in fixed relationship thereto disposed to close and open said second passageway after finite movement of the hammer in power and return strokes, respectively, said valve closure elements being cooperable to apply pressure from fluid in the housing alternately to said endwise surfaces of the hammer and to reduce pressure on the endwise surface opposite to the one upon which pressure is applied; and a check valve at said inlet section of the housing biased against inlet pressure disposed to close all openings in said section simultaneously and prevent reverse flow of actuating fluid into the inlet, said check valve, housing, hammer and first valve closure member being cooperable to provide a closed small volume chamber in the housing when said first passageway is closed by said first valve closure member.

8. An impact tool powered by a compressible iiuid which comprises in combination a housing; an inlet for actuating fluid into the housing, including a section having a plurality of openings therethrough symmetrically arranged on the circumference of a circle; an anvil mounted in the housing for limited reciprocating movement; a hammer mounted between the inlet and anvil and reciprocable in the housing to beat upon the anvil, said hammer having endwise surfaces of different areas against which pressure from liuid in the housing can act to urge the hammer in power and return strokes; a first fluid passageway through the hammer extending between said surfaces; a second uid passageway through the anvil extending from a surface of the anvil opposed to the hammer to the exterior of the tool; a first valve closure member carried by the housing in fixed position disposed to open and close said first passageway after finite movetively; a second valve closure member carried by the hammer in fixed relationship thereto disposed to close and open said second passageway after finite movement of the hammer in power and return strokes, respectively, said valve closure elements being cooperable to apply pressure from uid in the housing alternately to said endwise surfaces of the hammer and to reduce pressure on the endwise surface opposite to the one upon which pressure is applied; and an annular check valve closure member biased against inlet pressure disposed to close all openings in said inlet section simultaneously and prevent reverse ow of actuating fluid into the inlet, said check valve, housing, hammer and first valve closure member being cooperable to provide a closed small volume chamber in the housing when said first passageway is closed by said first valve closure member.

9. The impact tool of claim 8 wherein the check Valve closure member has guide fins slidably disposed in each of said openings maintaining the valve closure member centered on each of the openings.

10. The impact tool of claim 9 wherein-the valve closure member is biased against inlet pressure by a plurality of springs singly disposed in each of said openings and maintaining balanced tension on the said closure member.

11. An impact tool powered by a compressible fluid which comprises in combination a housing; an inlet for actuating iiuid into the housing; van anvil mounted in casarse the housing for limited reciprocating movement; a harnmer mounted between the inlet and anvil and reciprocable in the housing to beat upon the anvil, said hammer having endwise surfaces of different areas against which pressure from fluid in the housing can act to urge the hammer in power and return strokes; a` iirst fluid passageway through the hammer extending between said surfaces; a second liuid passageway through the anvil extending from a surface of the anvil opposed to the hammer to the exterior of the tool; a irst valve closure means carried by the housing, including a reciprocable iinger disposed to enter and close said first passageway, and means for reciprocating the linger between advanced and retracted positions, disposed to advance Vthe linger Vafter the hammer has moved through an initial part of a return stroke and to retract the iinger after the hammer has moved through an initial part of a power stroke; a second valve closure means carried by the han-nier disposed to close and open said second passageway after linite movement of the hammer in power and return strokes, respectively, said valve closure means being cooperable to apply pressure from the iluid in the housing alternately to said endwise surfaces of the hammer and to reduce pressure on the endwise surface opposite to the one upon which pressure is applied; and a check valve in an inlet section of the housing biased against inlet pressure arranged to prevent reverse flow of actuating iiuid into the inlet, said check valve, housing, hammer and iirst valve closure member being cooperable to provide a closed small volume chamber in the housing when said iirst passageway is closed by said first valve closure member.

12. The impact tool of claim 11 wherein the check Valve closure member has guide fins slidably disposed in each of said openings maintaining the valve closure member centered on each of the openings.

13. The impact tool of claim 11 wherein the valve closure member is biased against inlet pressure by a plurality of springs singly disposed in each of said openings and maintaining balanced tension on said closure member.

14. An impact tool powered by a compressible Vfluid which comprises in combination a housing; an inlet for actuating iiuid into the housing including a section having a plurality of openings therethrough; an anvil mounted in the housing for limitedreciprccating movement; a hammer mounted between the inlet and anvil and reciprocable in the housing to beat upon the anvil, said hammer having endwise surfaces of diterent areas against which pressure from tiuid in the housing can act to urge the hammer in power and return strokes; a irst iiuid passageway through the hammer` extending between said surfaces; a second iiuid passageway through the anvil extendingy from a surface of the anvil opposed to the hammer to the exterior of the tool; a rst valve closure means carried by the housing including a reciprocable finger disposed to enter and close said iirst passageway, and means for reciprocating the linger between advanced and retracted positions, advancing the finger after the hammer has moved through an initial part of a return stroke and retracting the linger after the hammer has moved through an initial part of a power stroke; a second valve closure means carried by the hammer, disposed to close and open said second passageway after iinite movement of the hammer in power and return strokes, respectively, said valve closure means being cooperable to apply pressure from fluid in the housing alternately to said endwise surfaces of the hammer and to reduce pressure on the endwise surface opposite to the one upon which pressure is applied; and a check valve biased against inlet pressure disposed in said inlet section of the housing arranged to prevent reverse iiow of actuating iuid into the inlet, Vsaid check valve, housing, hammer and first valve closure member being cooperable to provide a closed small volume chamber in the housing when said first passageway is closed by said lirst valve closure member.

15. An impact tool powered by a compressible fluid which comprises in combination a housing; an inlet for actuating uid into the housing including a section having a plurality of openings therethrough symmetrically arranged on the circumference of a circle; an anvil mounted in the housing for limited reciprocating movement; a hammer mounted between the inlet and anvil and reciprocable in the housing to beat upon the anvil, said hammer having endwise surfaces of different areas against which pressure from the fluid in the housing can act to urge the hammer in power and return strokes; a

first fluid passageway through the hammer extending between said surfaces; a second uid passagewaythrough the anvilrextending from the surface of the anvil opposed to the hammer to the exterior of the tool; a first valve closure means carried by the housing, including a reciprocable hoger disposed to enter and close said first passageway, and means for reciprocating the finger between advanced and retracted position advancing the linger after the hammer has moved through an initial part of a return stroke and retracting the linger after the hammer has moved through an initial part of a power stroke; a second valve closure means carried by the hammer in lixed relationship thereto disposed to close and open said second passageway after finite movement of the hammer in power and return strokes, respectively, said valve closure means being cooperable to apply pressure from uid in the housing alternately to said endwise surfaces of the hammer and to reduce pressure on the endwise surface opposite the one upon which pressure is applied; and an annular check Valve closure member disposed to close all openings in said inlet section simultaneously when pressure on the hammer face nearest the inlet is lower than inlet pressure by a predetermined amount, said check valve, housing, hammer and iirst valve closure member being cooperable to provide a closed small volume chamber in the housing when said irst passageway is closed by said first valve closure member.

References Cited in the tile of this patent UNITED STATES PATENTS Wilder July 26, 1962 

1. AN IMPACT TOOL POWERED BY A COMPRESSIBLE FLUID WHICH COMPRISES IN COMBINATION A HOUSING; AN INLET FOR ACTUATING FLUID INTO THE HOUSING; AN ANVIL MOUNTED IN THE HOUSING FOR LIMITED RECIPROCATING MOVEMENT; A HAMMER MOUNTED BETWEEN THE INLET AND ANVIL AND RECIPROCABLE IN THE HOUSING TO BEAT UPON THE ANVIL, SAID HAMMER HAVING ENDWISE SURFACES OF DIFFERENT AREAS AGAINST WHICH PRESSURE FROM FLUID IN THE HOUSING CAN ACT TO URGE THE HAMMER IN POWER AND RETURN STROKES; A FIRST FLUID PASSAGEWAY THROUGH THE HAMMER EXTENDING BETWEEN SAID SURFACES; A SECOND FLUID PASSAGEWAY THROUGH THE ANVIL EXTENDING FROM A SURFACE OF THE ANVIL OPPOSED TO THE HAMMER TO THE EXTERIOR OF THE TOOL; A FIRST VALVE CLOSURE MEMBER, CARRIED BY THE HOUSING, DISPOSED TO OPEN AND CLOSE SAID FIRST PASSAGEWAY AFTER FINITE MOVEMENT OF THE HAMMER IN POWER AND RETURN STROKES, RESPECTIVELY; A SECOND VALVE CLOSURE MEMBER, CARRIED BY THE HAMMER, DISPOSED TO CLOSE AND OPEN SAID SECOND PASSAGEWAY AFTER FINITE MOVEMENT OF THE HAMMER IN POWER AND RETURN STROKES, RESPECTIVELY, SAID VALVE CLOSURE ELEMENTS BEING COOPERABLE TO APPLY PRESSURE FROM FLUID IN THE HOUSING ALTERNATELY TO SAID ENDWISE SURFACES OF THE HAMMER AND TOO REDUCE PRESSURE ON THE ENDWISE SURFACE OPPOSITE TO THE ONE UPON WHICH PRESSURE IS APPLIED; AND A CHECK VALVE BIASED AGAINST INLET PRESSURE DISVERSE FLOW OF ACTUATING FLUID INTO THE INLET, SAID CHECK VALVE, HOUSING, HAMMER AND FIRST VALVE CLOSURE MEMBER BEING COOPERABLE TO PROVIDE A CLOSED SMALL VOLUME CHAMBER IN THE HOUSING WHEN SAID FIRST PASSAGEWAY IS CLOSED BY SAID FIRST VALVE CLOSURE MEMBER. 